pm2 error: unknown option `--auto-exit'

Kubernetes cluster panic!!! App down!!! Libraries changes cause these specially when you do not make sure you use specific package versions. Our docker had just the below configuration which of course will deploy latest version of pm2:

...
RUN npm install pm2 -g
RUN pm2 update
...
CMD ["pm2-docker", "start", "--auto-exit", "process.yml"]

Not only pm2-docker was renamed to pm2-runtime (a symlink still exists) but in addition the --auto-exit flag does not exist any longer. Now you need to specify --no-auto-exit if needed.